The invention relates to a process and a device allowing material and heat to be transferred between a gas phase and one or two liquid phases and simultaneously allowing heat exchanges with another fluid.
This invention employs a device having several compartments delimited in particular by a stack of several flat plates, each plate being spaced apart from the next plate. This separation space may be occupied by corrugated plates. This type of arrangement is already used to carry out heat exchanges. The fluids circulate in passages formed between two adjacent plates. These passages are alternate and allow co-current circulation between the hot flow and the cold flow, or counter-current circulation. This type of exchanger improves the heat transfer coefficient but does not allow material to be transferred.
In general, the technology developed for making such heat exchanges is widely known. As stated, these exchangers are composed of a stack of stamped sheet metal. The space between the plates is filled with spacers composed of baffles formed directly in the sheet metal by stamping, or by spacer plates called waves, made of straight metal.
The spacer waves maintain a uniform spacing between the plates, and some of them create a secondary exchange surface. In general, the spacer waves increase the rate of flow, and improve the ability of the system to withstand pressure. All these metal sheets are joined to each other either by welding or by brazing, which provides a good seal between the plates but makes it practically impossible to clean the assembly mechanically, or by bolting which makes it necessary to use gaskets between the plates to prevent communication between the two fluids and leakage to the outside. Whatever the type of these systems, they all improve, to a greater or lesser degree, the specific exchange surface and the heat transfer coefficient.
All the inlets to the compartments receive the same fluid (for example, hot fluid), communicate with each other, and are in communication with a box called the exchange header. This box is joined to the assembly either by welding or by bolting with a gasket. The same type of assembly is performed for the outlet connections. Thus, in general, an exchanger supplied with two different fluids has four headers, two inlet headers, one for each fluid, and two outlet headers, one for each fluid.
The prior art, U.S. Pat. No. 3,568,462, also teaches circulating a film of condensed liquid flowing downward and a vapor phase flowing upward in compartments through a perforated horizontal plate or wave.
However, such a device has its drawbacks. It generates a substantial pressure loss since the fluids are forced to pass through horizontal plates. Such an arrangement requires the size of the perforations to be increased, to the detriment of the quality of the gas-liquid contact, the flowrates treated, and the mechanical rigidity of the device.